Figure 1

Estimating the location of the R wave peak for a QRS complex with an artifact: (a) signal s with a motion artifact (indicated with a circle) and differentiated signal with a step size of 1 sample, s’ ₁ (in bold) with maximum and minimum derivative values indicated by up- and down-pointing triangles, respectively; (b) differentiated signal with a step size Δ of 10 samples, s’ _Δ (in bold); (c) tangents to the ascending and descending slopes of the QRS complex, y _A and y _D , with the peak localized by their intersection.